Tumor antigen

ABSTRACT

Tumor antigen inducing and/or activating HLA-A2-restricted tumor-specific cytotoxic T lymphocytes that is activated by recognizing HLA-A2 and a tumor antigen peptide, and a peptide or polypeptide derived from the tumor antigen, a polynucleotide encoding the peptide or a complementary strand polynucleotide thereof, a transformant comprising a recombinant vector which comprises the polynucleotide are provided.

This is a Divisional of application Ser. No. 10/353,929 filed Jan. 30, 2003 (now U.S. Pat. No. 7,148,326); the entire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a tumor antigen, and more particularly relates to a peptide or a polypeptide recognized by tumor-specific cytotoxic T lymphocytes, a polynucleotide encoding the peptide or the polypeptide and a complementary strand polynucleotide thereto, a recombinant vector comprising the polynucleotide, a transformant comprising the recombinant vector, an antibody against the peptide or the polypeptide, a compound having any interaction with the peptide or the polypeptide or the polynucleotide, a cytotoxic T lymphocyte inducer consisting of the peptide and/or the polypeptide, and a pharmaceutical composition comprising the same, and a method for producing the polypeptide, a method for screening for a compound having any interaction with the peptide or the polypeptide or the polynucleotide, a method for inducing cytotoxic T lymphocytes using the peptide or the polypeptide, a method for measuring the peptide or the polypeptide or the polynucleotide encoding the polypeptide, and a reagent kit used for the measuring method.

BACKGROUND OF THE INVENTION

The immune system, particularly cytotoxic T lymphocytes (which, hereinafter, may be abbreviated to CTLs) play an important role in the exclusion of cancer in vivo. Infiltration of cytotoxic T lymphocytes exhibiting a cytotoxic activity against tumor cells has been detected at the tumor site of a cancer patient (Arch. Surg., 126:200-205, 1990.) A target molecule (tumor antigen) of the tumor-specific cytotoxic T lymphocytes was first discovered in a melanoma. A tumor antigen generated in a tumor cell is degraded in the cell into a peptide (tumor antigen peptide) consisting of 8 to 11 amino acids, which binds to a human leukocyte antigen (HLA) molecule that is the major histocompatibility complex antigen to be displayed on the surface of the tumor cell. The cytotoxic T lymphocytes recognize a complex consisting of HLA and the tumor antigen peptide, and damage the tumor cell. In other words, the cytotoxic T lymphocytes recognize the tumor antigen peptide in an HLA-restricted manner.

HLA is a cell membrane antigen, and is expressed on almost all eukaryotic cells. HLA is mainly classified into class I antigen and class II antigen. The HLA recognized by the cytotoxic T lymphocytes together with an antigen peptide belongs to class I antigens. HLA class I antigens are further classified into HLA-A, HLA-B, HLA-C, and so on. It was reported that HLA has genetic polymorphism. The HLA-A2 allele, which is one of polymorphisms of HLA-A subregion, is found in approximately 23% of African Blacks, approximately 53% of Chinese, approximately 40% of Japanese, approximately 49% of Northern Caucasians, and approximately 38% of Southern Caucasians.

As used herein, a tumor antigen means a protein, a polypeptide, or a peptide, which constitutes part of the tumor cell and is capable of inducing tumor-specific cytotoxic T lymphocytes. A tumor antigen peptide means a peptide that is generated as a result of degradation of the tumor antigen in a tumor cell and can induce or activate tumor-specific cytotoxic T lymphocytes upon being expressed on the cell surface by binding to an HLA molecule. In addition, the site of the amino acid sequence which is capable of inducing tumor-specific cytotoxic T lymphocytes that is present in a tumor antigen is called a tumor antigen epitope (tumor antigen determinant.)

In recent years, many genes encoding tumor antigens that can be recognized by cytotoxic T lymphocytes have been identified from cDNA of human tumor cells (Science 254:1643-1647, 1991; J. Exp. Med. 183:1185-1192, 1996; J. Immunol. 163:4994-5004, 1999.) Some of these genes are involved in cellular proliferation and malignant transformation, including HER/neu (Proc. Natl Acad. Sci. USA, 92:432-436, 1995) mutant cdk (Science, 269:1281-1284, 1995) mutant CASP-8 (J. Exp. Med., 186:785-793, 1997) and so on.

On the other hand, a molecule such as a tumor rejection antigen gene and a T cell antigen receptor (TCR), which are involved in specific immunity, have been identified in melanoma, esophageal cancer, and other cancers in the past 10 years, and a specific immunotherapy of advanced cancer or metastatic cancer has been studied using the peptide.

Now, in Europe and in the United States, cancer vaccine therapy has been developed in which cytotoxic T lymphocytes are activated by an administration of a tumor antigen in a cancer patient. Results from a clinical test of a melanoma specific tumor antigen have been reported. For example, administration of a melanoma antigen gp-100 peptide subcutaneously to melanoma patients along with administering interleukin-2(IL-2) intravenously gave a tumor regression in 42% of the patients (Nature Medicine, 4:321, 1998.) In this way, by utilizing a tumor antigen as a vaccine, an effective treatment against cancer can be achieved.

However, almost all of the identified tumor antigens are derived from melanomas. Tumor antigens derived from epithelial cancers and adenocarcinomas, such as pancreatic cancer, which occur at high incidence rates, have been reported for such specific immunotherapy only in a few papers. Pancreatic cancer is one of the largest causes of death by cancer in the world and causes about 27,000 deaths a year in the USA and about 50,000 deaths in Europe. The main factors causing these large numbers of deaths are lack of an effective therapeutic method, the difficulty of diagnosis, and the activity of this cancer. Only 1 to 4% of pancreatic cancer patients have overcome the disease, and the incidence substantially equals the death rate. Therefore, a new approach of therapy, for example, development of specific immunotherapy is needed.

In addition, in view of the diversity of cancer, an identical tumor antigen should not be expressed in the same degree in all cancer cells Naturally, cancer vaccine therapy by activating the cytotoxic T lymphocytes using one kind of tumor antigen has a therapeutic effect on cancer having the tumor antigen. However, in order to induce and activate the tumor antigen-specific cytotoxic T lymphocytes and obtain a high therapeutic effect corresponding to the diversity of cancer, it is important to discover and use many novel tumor antigens in accordance with the diversity of cancer.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a peptide consisting of an amino acid sequence according to any one of those from SEQ ID NO: 1 to SEQ ID NO: 44 is provided.

In another embodiment of the present invention, a polypeptide consisting of an amino acid sequence according to any one of those from SEQ ID NO: 45 to SEQ ID NO: 53 is provided.

In still another embodiment of the present invention, a composition comprising one or more of peptides or polypeptides selected from the peptides, which consist of the amino acid sequence according to any one of those from SEQ ID NO:1 to SEQ ID NO:44, and the polypeptides, which consist of an amino acid sequence according to any one of those from SEQ ID NO:45 to SEQ ID NO:53 is provided.

In an additional embodiment of the present invention, an anti-cancer vaccine comprising one or more of peptides or polypeptides selected from the peptides, which consist of the amino acid sequence according to any one of those from SEQ ID NO:1 to SEQ ID NO:44, and the polypeptides, which consist of an amino acid sequence according to any one of those from SEQ ID NO:45 to SEQ ID NO:53 is provided.

In yet another embodiment of the present invention, an anti-cancer vaccine comprising one or more of peptides or polypeptides selected from the peptides, which consist of the amino acid sequence according to any one of those from SEQ ID NO:1 to SEQ ID NO:44, and the polypeptides, which consists of an amino acid sequence according to any one of those from SEQ ID NO:45 to SEQ ID NO:53, for use in the treatment of pancreatic cancer, colon cancer, or stomach cancer is provided.

In another embodiment of the present invention, an inducer of cytotoxic T lymphocytes comprising one or more of peptides or polypeptides selected from the peptides, which consist of the amino acid sequence according to any one of those from SEQ ID NO:1 to SEQ ID NO: 44, and the polypeptides, which consist of an amino acid sequence according to any one of those from SEQ ID NO:45 to SEQ ID NO:53 is provided.

In still another embodiment of the present invention, a method for inducing cytotoxic T lymphocytes using one or more of peptides or polypeptides selected from the peptides, which consist of the amino acid sequence according to any one of those from SEQ ID NO:1 to SEQ ID NO:44, and the polypeptides, which consist of an amino acid sequence according to any one of those from SEQ ID NO:45 to SEQ ID NO:53 is provided.

In an additional embodiment of the present invention, a polynucleotide encoding a peptide or a polypeptide consisting of the amino acid sequence according to any one of those from SEQ ID NO:1 to SEQ ID NO:53, or the complementary strand thereof is provided.

In yet another embodiment of the present invention, a polynucleotide according to any one of those from SEQ ID NO:54 to SEQ ID NO:62, or the complementary strand thereof is provided.

In another embodiment of the present invention, a polynucleotide according to any one of those from SEQ ID NO:54 to SEQ ID NO:62, wherein a polypeptide encoded by the polynucleotide induces cytotoxic T lymphocytes and/or is recognized by cytotoxic T lymphocytes, or the complementary strand thereof is provided.

In still another embodiment of the present invention, a polynucleotide that hybridizes to the polynucleotide or the complementary strand thereof under stringent conditions is provided.

In an additional embodiment of the present invention, a recombinant vector comprising the polynucleotide or the complementary strand thereof or the polynucleotide that hybridizes to the polynucleotide or the complementary strand thereof under stringent conditions is provided.

In yet another embodiment of the present invention, a recombinant expression vector comprising the polynucleotide or the complementary strand thereof or the polynucleotide that hybridizes to the polynucleotide or the complementary strand thereof under stringent conditions is provided.

In another embodiment of the present invention, a transformant transformed with the recombinant vector or the recombinant expression vector, which comprises the polynucleotide or the complementary strand thereof or the polynucleotide that hybridizes to the polynucleotide or the complementary strand thereof under stringent conditions is provided.

In still another embodiment of the present invention, a method for producing the polypeptide, which comprises culturing the transformant transformed with the recombinant expression vector that comprises the polynucleotide or the complementary strand thereof or the polynucleotide that hybridizes to the polynucleotide or the complementary strand thereof under stringent conditions is provided.

In an additional embodiment of the present invention, an antibody that immunologically recognizes the peptide or the polypeptide is provided.

In yet another embodiment of the present invention, a method for screening for a compound that enhances at least recognition of the peptide or the polypeptide by HLA-A2-restricted cytotoxic T lymphocytes, by interacting with the peptide or the polypeptide and/or HLA-A2 to enhance, and/or the compound that enhances expression of the polynucleotide or the complementary strand thereof by interacting with the same, is provided wherein the method uses at least one selected from a group consisting of the peptide, the polypeptide, the polynucleotide, the complementary strand thereof, the recombinant vector, the recombinant expression vector, the transformant, and the antibody.

On another embodiment of the present invention, a compound obtained by the method for screening a compound that enhances at least recognition of the peptide or the polypeptide by HLA-A2-restricted cytotoxic T lymphocytes, by interacting with the peptide or the polypeptide and/or HLA-A2 to enhance, and/or the compound that enhances expression of the polynucleotide or the complementary strand thereof by interacting with the same, is provided wherein the method uses at least one selected from a group consisting of the peptide, the polypeptide, the polynucleotide, the complementary strand thereof, the recombinant vector, the recombinant expression vector, the transformant, and the antibody.

In still another embodiment of the present invention, a compound that enhances recognition of at least one of the peptide or the polypeptide by the HLA-A2-restricted cytotoxic T lymphocytes, or the compound that enhances the expression of the polynucleotide or the complementary strand thereof by interacting with the same is provided.

In an additional embodiment of the present invention, a pharmaceutical composition used for cancer treatment, comprising at least one selected from a group consisting of the peptide, the polypeptide, the polynucleotide, the complementary strand thereof, the recombinant vector, the recombinant expression vector, the transformant, the antibody, and the compound is provided.

In yet another embodiment of the present invention, use of the composition, the anti-cancer vaccine, the inducer of the cytotoxic T lymphocytes, or the pharmaceutical composition for cancer disease is provided.

In another embodiment of the present invention, a method for measuring quantitatively or qualitatively the peptide or the polypeptide, or the polynucleotide is provided.

In still another embodiment of the present invention, a reagent kit used in the method for measuring quantitatively or qualitatively the peptide or the polypeptide, or the polynucleotide, is provided wherein the kit comprises at least one selected from a group consisting of the peptide, the polypeptide, the polynucleotide or the strain thereof, or the antibody.

In an additional embodiment of the present invention, use of a reagent kit for a test of the cancer disease is provided, wherein the kit is used to measuring quantitatively or qualitatively the peptide or the polypeptide, or the polynucleotide, comprises at least one selected from a group consisting of the peptide, the polypeptide, the polynucleotide or the complementary strain thereof, or the antibody.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates that OK-CTLp (HLA-A0207/A3101) lyses tumor cells in an HLA-A2-restricted manner.

FIG. 2 illustrates that recognition of the human pancreatic adenocarcinoma cell line Panc-1 by OK-CTLp and interferon-γ production as a result thereof is an HLA-A2-restricted event.

FIGS. 3A-3B illustrate that OK-CTLp recognizes COS7 cells, in which each of cDNA clones 1 to 6 (FIG. 3A) and cDNA clone 7 (FIG. 3B), obtained from the human pancreatic adenocarcinoma cell line Panc-1, was coexpressed with HLA-A2, in an HLA-A2-restricted manner.

FIGS. 4A-4F illustrate that cDNA clones 1 to 6, obtained from the human pancreatic adenocarcinoma cell line Panc-1, are recognized by OK-CTLp in a dose-dependent manner. FIGS. 4A-4F each show that OK-CTLp recognizes COS7 cells, in which each of cDNA clones 1 to 6, having high homology with UBE2V, HNRPL, WHSC2, EIF4EBP1, ppMAPkkk, and 2-5 OAS3, respectively, was coexpressed with HLA-A2, in an HLA-A2-restricted manner. The symbol—▪—shows the amount of interferon-γ produced by OK-CTLp, when the HLA-A0207 gene was coexpressed with the each tumor antigen gene in target cells,—⋄—shows the amount of interferon-γproduced by OK-CTLp, when the HLA-A2402 gene was coexpressed with each tumor antigen gene in the target cells.

FIG. 5 illustrates that OK-CTLp or OK-CTL clone recognizes five peptides derived from a gene product of the tumor antigen gene 1 that is obtained from the human pancreatic adenocarcinoma cell line Panc-1, which has high homology with UBE2V.

FIG. 6 illustrates that OK-CTLp or OK-CTL clone recognizes four peptides derived from a gene product of the tumor antigen gene 2 that is obtained from the human pancreatic adenocarcinoma cell line Panc-1, which has high homology with HNRPL.

FIG. 7 illustrates that OK-CTLp or OK-CTL clone recognizes four peptides derived from a gene product of the tumor antigen gene 3 that is obtained from the human pancreatic adenocarcinoma cell line Panc-1, which has high homology with WHSC2.

FIG. 8 illustrates that OK-CTLp or OK-CTL clone recognizes two peptides derived from a gene product of the tumor antigen gene 4 that is obtained from the human pancreatic adenocarcinoma cell line Panc-1, which has high homology with EIF4EBP1.

FIG. 9 illustrates that OK-CTLp or OK-CTL clone recognizes three peptides derived from a gene product of the tumor antigen gene 5 that is obtained from the human pancreatic adenocarcinoma cell line Panc-1, which has high homology with ppMAPkkk.

FIG. 10 illustrates that OK-CTLp or OK-CTL clone recognizes one peptide derived from a gene product of the tumor antigen gene 6 that is obtained from the human pancreatic adenocarcinoma cell line Panc-1, which has high homology with 2-5 OAS3.

FIGS. 11A-11F illustrate representative peptides showing that the tumor antigen peptides, which are derived from products of the tumor antigen genes obtained from the human pancreatic adenocarcinoma cell line Panc-1, are recognized by OK-CTL clone in a dose-dependent manner. FIGS. 11A-11F show that OK-CTLp recognizes the peptides which are derived from gene products of the tumor antigen genes 1 to 6, having high homology with UBE2V, HNRPL, WHSC2, EIF4EBP1, ppMAPkkk, and 2-5 OAS3, respectively.

FIGS. 12A-12C illustrate that three peptides derived from a gene product of the tumor antigen gene 1 having high homology with UBE2V can induce CTL showing cytotoxicity against HLA-A2⁺ tumor cell, from peripheral blood mononuclear cells of a cancer patient. The symbol—▪—shows the human pancreatic adenocarcinoma cell line Panc-1 (HLA-A0201/1101,)—♦—shows the human colon adenocarcinoma cell line SW620 (HLA-A0201/2402,)—ο—shows the HLA-A2 ⁻ lung adenocarcinoma cell line RERF-LC-MS (HLA-A1101/1101,)—Δ—shows an EBV transformed autologous B cell (HLA-A0207/3101,) and—□—shows a PHA blast of autologous T cell (HLA-A0207/3101.) These symbols are also used in the same manner in FIGS. 13 to 17 described below.

FIGS. 13A-13B illustrate that two peptides derived from a gene product of the tumor antigen gene 2 having high homology with HNRPL can induce CTL showing cytotoxicity against HLA-A2⁺ tumor cell, from peripheral blood mononuclear cells of a cancer patient.

FIGS. 14A-14B illustrate that two peptides derived from a gene product of the tumor antigen gene 3 having high homology with WHSC2 can induce CTL showing cytotoxicity against HLA-A2⁺ tumor cell, from peripheral blood mononuclear cells of a cancer patient.

FIGS. 15A-15B illustrate that two peptides derived from a gene product of the tumor antigen gene 4 having high homology with EIF4EBP1 can induce CTL showing cytotoxicity against HLA-A2⁺ tumor cell, from peripheral blood mononuclear cells of a cancer patient.

FIG. 16 illustrates that one peptide derived from a gene product of the tumor antigen gene 5 having high homology with ppMAPkkk can induce CTL showing cytotoxicity against HLA-A2⁺ tumor cell, from peripheral blood mononuclear cells of a cancer patient.

FIG. 17 illustrates that one peptide derived from a gene product of the tumor antigen gene 6 having high homology with 2-5 OAS3 can induce CTL showing cytotoxicity against HLA-A2⁺ tumor cell, from peripheral blood mononuclear cells of a cancer patient.

FIGS. 18A-18E illustrate that tumor antigen peptides can induce CTL, which shows cytotoxic activity in an HLA-A2-restricted manner and in a dose-dependent manner, from peripheral blood mononuclear cells of a cancer patient. FIGS. 18A-18E each show that peptides derived from gene products of the tumor antigen genes 1 to 5, having high homology with UBE2V, HNRPL, WHSC2, EIF4EBP1, and ppMAPkkk, respectively, induces CTL that recognizes the peptide in a HLA-A2-restricted manner, from peripheral blood mononuclear cells of a cancer patient. The symbol—▪—shows T2 cells in which the tumor antigen peptide was made to express—⋄—and shows autologous PHA blastoid T cells.

FIGS. 19A-19B illustrate that gene products of the tumor antigen genes KM-PA-2 (FIG. 19A) and KM-PA-4 (FIG. 19B), which were obtained from the human pancreatic adenocarcinoma cell line CFPAC-1, are recognized by OK-CTLp in an HLA-A2-restricted manner.

FIGS. 20A-20B show that peptides derived from the tumor antigen genes KM-PA-2 and KM-PA-4, respectively, which were obtained from the human pancreatic adenocarcinoma cell line CFPAC-1, can induce CTL from peripheral blood mononuclear cells (PBMC) of a cancer patient, which shows cytotoxicity against T2 cells which have been pulsed with the peptide corresponding to the peptide used for stimulating the PBMC (left-hand of FIGS. 20A-20B,) and an HLA-A2⁺ tumor cell Panc-1 (right-hand of FIGS. 20A-20B.) FIGS. 21A-21C show that CTL, which was induced from peripheral blood mononuclear cells of a cancer patient by peptide derived from the tumor antigen gene KM-PA-2 obtained from the human pancreatic adenocarcinoma cell line CFPAC-1, lyses tumor cells in an HLA-A2-restricted manner.

DETAILED DESCRIPTION OF THE INVENTION

In order to identify a tumor rejection antigen gene and a tumor antigen encoded by the gene, which can be used for specific imnunotherapy for pancreatic cancer, HLA-A2-restricted tumor-specific cytotoxic T lymphocytes have been established in the present invention that are activated by recognizing HLA-A2 and a tumor antigen peptide (hereafter, this cell may be called OK-CTLp) from a colon cancer patient, and genes encoding tumor antigens, which can be recognized by these tumor-specific cytotoxic T lymphocytes (CTL,) have been isolated/identified from a cDNA library of Panc-1 cell that as the human pancreatic adenocarcinoma cell line using the gene expression cloning method. In the present invention, genes have also been identified, which can be recognized by CTL in the same way as described above, from genes identified as those encoding the tumor antigen by the SEREX (Serological analysis of recombinant cDNA expression libraries) method (Proc. Natl Acad. Sci. USA, 92:11910-11813, 1995.) In addition, based on the tumor antigen encoded by the gene obtained, a peptide having the tumor antigen epitope has been found in the present invention.

As used herein, a polypeptide means a long chain peptide of arbitrary peptides comprising two or more amino acids bound to each other by a peptide bond or by a modified peptide bond. For example, a protein is included in the definition of polypeptide herein. Moreover, a short chain peptide sometimes called an oligopeptide or an oligomer is simply called a peptide herein.

“Recognize” herein means that a subject distinguishes an object from others and cognates it, for example, binds to the object cognized. Particularly, in the present invention, CTL which recognize the tumor cells or the tumor antigen peptides means that CTL binds through a T cell receptor to the tumor antigen peptides that are presented by HLA.

“Activate” herein means to enhance or to make it work further a thing or a state, which has an activity or an action. Particularly, in the present invention, activation of CTL means that CTL recognizes an antigen being presented by HLA to produce IFN-γ or CTL shows cytotoxicity against the target cells recognized by CTL.

“Induce” herein means to generate an activity or an action from a thing or a state that are in a phase merely having the activity or the action. Particularly, in the present invention, induction of an antigen-specific CTL means to make CTL, which specifically recognizes a certain antigen differentiate and/or proliferate in vitro or in vivo. In addition, the inducer of cytotoxic T lymphocytes in the present invention means a composition which changes the state, where CD8-positive T lymphocytes specifically recognizing a certain antigen is absent or present in a very low degree, to the state, where the cytotoxic T lymphocytes recognizing the antigen is present in a very degree.

(Isolation and Identification of the Tumor Antigen Gene, Tumor Antigen, and Tumor Antigen Peptide)

In the present invention, OK-CTLp that was HLA-A2-restricted cytotoxic T lymphocyte described above was used as an effector cell and tumor antigens capable of activating this cell were isolated and identified by using the gene expression cloning method. In other words, cDNA of the human pancreatic adenocarcinoma cell line Panc-1 and cDNA of HLA-A0207 were cotransfected into COS-7 cells, and among those cells in which the transfected genes were expressed, the cells which enhance IFN-γ production from OK-CTLp were selected, and hence, the gene encoding the tumor antigen capable of activating CTL was identified. The method will be presented in more detail in examples described herein. As a result, seven cDNA clones were obtained which were recognized by OK-CTLp in an HLA-A2-restricted manner.

In addition, two genes, KM-PA-2 and KM-PA-4, encoding tumor antigens capable of activating CTL in an HLA-A2-restricted manner were found in the same manner as described above from the genes encoding the tumor antigens, were detected from a cDNA library of the human pancreatic adenocarcinoma cell line CFPAC-1 using the SEREX method and already reported (Biochim. Biophys. Res. Commun., 281:936-944, 2001,). The SEREX method is a method that can be applied to detection of a tumor antigen. However, among 1500 or more kinds of tumor antigens detected by this method, those being identified as tumor antigens capable of inducing both cell-mediated immunity and humoral immunity are only MAGE-1, tyrosinase, and NY-ESO-1. Thus, the tumor antigen identified by the SEREX method cannot always activate CTL. The present invention first revealed that the tumor antigen genes described above, KM-PA-2 and KM-PA-4, can activate CTL in an HLA-A2-restricted manner.

All seven cDNA clones described above, which were obtained from Panc-1 cell, contained a complete open reading frame (ORF). The nucleotide base sequence of these genes was determined by the Sanger method (Chaih Terminator method) to estimate the amino acid sequence on the basis of the nucleotide base sequence. When a homology search was carried out for these nucleotide base sequences and deduced amino acid sequences in an existing database such as GenBank, it was found that these genes were cDNAs whose nucleotide base sequences are novel, though they have high homology with genes as described below. There is no report on the known homologous genes functioning as a tumor antigen. With regard to clone 3 among the 7 cDNA clones (clones 1 to 7) obtained, the sequence of an initial clone, which was obtained by the gene expression cloning method described above, and has high homology with that of a gene of Wolf-Hirschhorn syndrome candidate 2 protein (WHSC2), was 25 bp shorter at the 5′-terminal region than that of WHSC2, so that full-length cDNA was obtained from the cDNA library of the Panc-1 cell by a standard colony hybridization method using the clone labeled with ³²p as a probe. Hereinafter, the genes of the Panc-1 cell, from which the above-described clones 1 to 7 were derived, will be called gene 1 to 7, respectively. Also, the polypeptides consisting of an amino acid sequence encoded by each gene are occasionally herein called gene product 1 to 7. Deduced amino acid sequences encoded by each of these genes are shown as SEQ ID NO:45 to SEQ ID NO:51, respectively, and the nucleotide base sequences thereof are shown as SEQ ID NO:54 to SEQ ID NO:60, respectively. The above described genes 1 to 6 and the gene 7 were registered at the DNA Data Bank of Japan (DDBJ) of the National Research Institute of Genetics in Jun. 12th, 2000 and Aug. 2nd, 2000, respectively (Table 1).

For KM-PA-2 and KM-PA-4, the homologous genes have been reported as shown in Table 1 (Biochem. Biophys. Res. Commun., 281:936-944, 2001.) The nucleotide base sequences of KM-PA-2 and KM-PA-4 are shown as SEQ ID NO: 52 and SEQ ID NO: 53, respectively, and the deduced amino acid sequences are shown as SEQ ID NO:61 and SEQ ID NO: 62, respectively.

TABLE 1 cDNA clone (gene) Polypeptide encoded by cDNA Base length (bp) Amino [DDBJ SEQ acid SEQ Homologous gene accession no.] ID: NO length ID: NO [GenBank accession no.] 1 1775 54 PP 1 270 45 ubiquitin-conjugated enzyme [AB044550] variant Kua (UBE2V) [AF155120] 2 2097 55 PP 2 589 46 heterogeneous nuclear [AB044547] ribonucleoprotein L (HNRPL) [NM_001533] 3 2243 56 PP 3 549 47 Wolf-Hirschhorn Syndrome [AB044549] candidate 2 protein (WHSC2) [AK001304] 4 831 57 PP 4 118 48 eIF-4E-binding protein 1 [AB044548] (EIF4EBP1) [NM_004095] 5 2404 58 PP 5 779 49 partial putatibe mitogen [AB044546] actibated protein kinase kinase kinase (ppMAPkkk) [AJ242724] 6 6707 59 PP 6 1087 50 2′,5′-oligoadenylate [AB044545] synthetase 3 (2-5 OAS3) [NM_006187] 7 769 60 PP 7 216 51 clevage and polyadenylation [AB046744] specificity factor (CPSF) [U37012] KM-PA-2 2060 61 PP-KM-PA-2 634 52 KIAA0124 gene [D50914] [AB060694] human homologue of mouse block of proliferatin 1(Bop1) [BC005160] KM-PA-4 1841 62 PP-KM-PA-4 142 53 coactosin-like protein (CLP) [L54057]

The nucleotide base sequence of gene 1 has high homology with that of the ubiquitin-conjugated enzyme variant Kua gene (UBE 2V) registered at GenBank (accession no.AF155120.) The length of the deduced amino acid (aa) encoded by gene 1 was slightly longer than that encoded by the UBE2V gene (3 aa in positions 109 to 111.) The function of UBE2V has not so far been reported.

The nucleotide base sequence of gene 2 has high homology with that of the heterogeneous nuclear ribonucleoprotein L (HNRPL) gene (accession no.NM_(—)001533.) However, the deduced amino acid length was slightly longer than that of the HNRPL gene at the N-terminal positions 1 to 31. The HNRPL gene product is a heterogeneous nuclear ribonucleoprotein complex and provides a substrate for the processing events that the mRNA precursor undergoes in the cytoplasm.

The nucleotide base sequence of gene 3 has high homology with that of the Wolf-Hirschhorn syndrome candidate 2 proteins (WHSC2) gene registered at GenBank (accession no.AK001304.) The WHSC2 gene seems to have some functions in the phenotype of WHS, a multiple malformation syndrome characterized by mental and developmental defects resulting from a partial deletion of the short arm of chromosome 4.

The nucleotide base sequence of gene 4 has high homology with that of the eIF-4E-binding protein 1 gene (EIF4EBP1, accession no.NM_(—)004095.) The product of EIF4EBP1 gene is known as a translation initiation factor that initiates insulin-dependent phosphorylation of 4E-BP1, making it available to form an active cap-binding complex.

The nucleotide base sequence of gene 5 has homology with that of the partial putative mitogen-activated protein kinase kinase kinase gene (ppMAPkkk, accession no.AJ242724) registered at GenBank. The deduced amino acid sequence encoded by gene 5 is 230 aa longer at the N-terminal and 258 aa longer at the C-terminal as compared with that of the registered ppMAPkkk gene (its function has not yet been reported.)

The nucleotide base sequence of gene 6 consists of 6707 bp and has homology with that of the 2′, 5′-oligoadenylate synthetase 3 gene (2-5 OAS3 gene, accession no.NM_(—)006187) with a total of 13-aa differences at positions 18, 159, 249, 287, 288, 316, 393 to 398, and 984. 2-5 OAS3 is known as an IFN-induced protein that plays an important role in immune-protection against microorganism infection.

The nucleotide base sequence of gene 7 has homology with positions 3701 to 4463 of the Human cleavage and polyadenylation specificity factor (CPSF, accession no.U37012) gene and the amino acid sequence is approximately 1226 aa shorter.

The nucleotide base sequence of gene KM-PA-2 has high homology with that of the KIAA0124 and human homologues of mouse block of proliferation 1 (Bop1.) The nucleotide base at position 1466 of the KIAA0124 gene is guanine (G) and thus, the amino acid residue of the 465^(th) position is histidine (H). On the contrary, in gene KM-PA-2, they are adenine (A) and arginine (R), respectively.

The nucleotide base sequence of gene KM-PA-4 and the amino acid sequence encoded by the gene are identical to those of coactosin-like protein (CLP.) In order to obtain tumor antigen peptides from the above-described 9 genes encoding a tumor antigen, peptides were designed and synthesized based on the amino acid sequences encoded by the above-described genes. For gene 7, the gene was regarded as a part of a gene consisting of a longer base sequence, so that the peptides, which were derived from the amino acid sequence encoded by the gene (CPSF) homologous to gene 7, were also designed and synthesized. It has been known that a tumor antigen peptide capable of binding to the HLA-A2 has a motif (a specific sequence) in its sequence. Then, at first, the peptide having an HLA-A2 binding motif (a specific sequence) was searched for in the literature (J. Immunol., 152:163, 1994; Immunogenetics, 41:178, 1994,) and the peptides of 9-mer to 11-mer, which were different from each other and suited to the motif obtained, were designed and synthesized based on the amino acid sequence encoded by the above described genes. Recognition of each peptide by CTL was measured using OK-CTLp or several kinds of OK-CTL clones obtained by cloning OK-CTLp by the limiting dilution method using IFN-γ production from these CTL as an indicator. The OK-CTL clones are the cells recognizing any one of the above-described genes 1 to 7. On the other hand, OK-CTLp recognizes any of genes 1 to 7. The results revealed that OK-CTLp is a cell population recognizing various kinds of tumor antigens. Therefore, when the OK-CTL clones were used to test the peptide for its ability to activate CTL, a clone was used which recognizes the product of the gene encoding the same peptide as that to be tested. Forty four peptides (SEQ ID NO:1 to SEQ ID NO:44; Table 2 and Table 3) among those synthesized were recognized by OK-CTLp or OK-CTL clones and enhanced IFN-γ production from CTL. Among these peptides, P1 to P5, P6 to P9, P10 to P13, P14 and P15, P16 to P18, and P19 are the peptides consisting of a partial sequence of the amino acid sequences encoded by gene 1, gene 2, gene 3, gene 4, gene 5, and gene 6, respectively, and encoded also by genes UBE2V, HNRPL, WHSC2, EIF4-EBP1, ppMAPkkk, and 2-5 OAS3 having high homology with each genes. On the other hand, P25, P26, P27, P28, P30, and P31 are the peptides consisting of a partial sequence of the amino acid sequences encoded by gene 7 and gene CPSF having high homology with gene 7. P20, P21, P22, P23, P24, P29, and P32 consist of a partial sequence of the amino acid sequence specific to CPSF.

TABLE 2 Position SEQ ID NO: of amino in Origin of acid Amino acid sequence Number peptide sequence sequence listing P1  Gene 1 43-51 RLQEWCSVI 1 P2  (UBE2V) 64-73 LLLLARWEDT 2 P3  85-93 LIADFLSGL 3 P4  201-209 LLQDWHVIL 4 P5  208-216 ILPRKHHRI 5 P6  Gene 2 140-148 ALVEFEDVL 6 P7  (HNRPL) 404-412 CLYGNVEKV 7 P8  443-451 FMFGQKLNV 8 P9  501-510 NVLHFFNAPL 9 P10 Gene 3 103-111 ASLDSDPWV 10 P11 (WHSC2) 141-149 ILGELREKV 11 P12 157-165 MLPLECQYL 12 P13 267-275 TLLRKERGV 13 P14 Gene 4 51-59 RIIYDRKFL 14 P15 (EIF4EBP1) 52-60 IIYDRKFLM 15 P16 Gene 5 290-298 QILKGLLFL 16 P17 (ppMAPkkk) 294-302 GLLFLHTRT 17 P18 432-440 DLLSHAFFA 18 P19 Gene 6 666-674 QQLCVYWTV 19 (2-5 OAS3) P20 CPSF 285-293 SLLYLNQSV 20 P21 CPSF 250-258 KVHPVIWSL 21 P22 CPSF 534-542 DMWTVIAPV 22 P23 CPSF 882-890 QLGQGNLKV 23 P24 CPSF 392-400 LLLKYTEKL 24 P25 Gene 7 1367-1375 TMLPHHAGL 25 P26 Gene 7 1296-1304 LLRRADFHV 26 P27 Gene 7 1401-1409 ELLNRYLYL 27 P28 Gene 7 1358-1366 LLMLQNALT 28 P29 CPSF 797-805 YQLPDWRLV 29 P30 Gene 7 1359-1368 LMLQNALTTM 30 P31 Gene 7 1358-1367 LLMLQNALTT 31 P32 CPSF 456-465 TQLATYSFEV 32

TABLE 3 Position SEQ ID NO: Origin of amino in of acid Amino acid sequence Number peptide sequence sequence listing P33 KM-PA-2 29-38 LEWYDDFPHV 33 P34 115-124 FSGDVMIHPV 34 P35 172-180 WAQEDPNAV 35 P36 179-188 AVLGRHKMHV 36 P37 326-335 RLWEVATARC 37 P38 348-356 VAWNPSPAV 38 P39 585-593 DLLQNPLLV 39 P40 586-595 LLQNPLLVPV 40 P41 612-621 VIFHPTQPWV 41 P42 KM-PA-4 15-24 NLVRDDGSAV 42 P43 57-65 RLFAFVRFT 43 P44 104-113 VVQNFAKEFV 44

These tumor antigen peptides are-presented on a cell surface by HLA-A2 and recognized by T cell receptor (TCR) expressed on the peptide-specific OK-CTL clone. The peptides derived from gene 1 and UBE2V, gene 2 and HNRPL, or gene 6 and 2-5 OAS3 are recognized by OK-CTL clone expressing TCR-Vβ 8.1, TCR-Vβ 3.2, or TCR-Vβ 14. In addition, Peptides derived from gene 3 and WHSC2, gene 4 and EIF4EBP1, or gene 5 and ppMAPkkk are recognized by OK-CTL clone expressing TCR-Vβ13, TCR-Vβ8.1, or TCR-Vβ18, respectively.

Two each of the OK-CTL clones that recognize peptides derived from gene 1 and UBE2V, gene 2 and HNRPL, and gene 6 and 2-5 OAS3 were expressed TCR possessing different complementarity-determining regions 3 (CDR 3; an element responsible for binding to antigenic epitopes on a groove of the HLA Class I molecules,) respectively. The OK-CTL clone recognizing peptides derived from gene 3 and WHSC2, gene 4 and EIF4EBP1, and gene 5 and ppMAPkkk also expressed TCR possessing the different CDR3, respectively.

Moreover, the above-described 44 peptides recognized by OK-CTLp each induced HLA-A2-restricted tumor-specific CTL in vitro from the peripheral blood mononuclear cells (which, hereinafter, may be abbreviated to PBMC) which are autologous cells derived from a colon cancer patient from whom OK-CTLp was obtained, and/or from the PBMC of HLA-A0201⁺ cancer patients (pancreatic cancer, colon cancer, and stomach cancer.) The above-described CTL induced from the peripheral blood mononuclear cells of the cancer patients lysed HLA-A2⁺ tumor cells in a dose-dependent manner. However, nolysis was observed in the HLA-A2⁻ tumor cell RERF-LC-MS, and HLA-A⁺ autologous EBV-B cells and HLA-A⁺ T cells stimulated by PHA, both of which are derived from normal cells. In addition, the above-described CTL showed cytotoxicity in a dose-dependent manner against the T2 cells that were pulsed with the same peptide as that used for stimulation.

On the basis of the examination described above, 44 tumor antigen peptides capable of activating OK-CTLp were obtained. Furthermore, it was found that these peptides could induce HLA-A2-restricted tumor-specific CTLs from PBMC derived from patients of pancreatic cancer, colon cancer, and/or stomach cancer. In addition, it was revealed that both the pancreatic adenocarcinoma cell line Panc-1 and the colon adenocarcinoma cell line SW620 are recognized by CTLp and by CTLs induced from PBMC by the above described peptide. This result suggests that pancreatic cancer and colon cancer have a common tumor antigen epitope recognized by host CTLs.

(Polypeptide and Peptide)

A polypeptide according to the present invention is a polypeptide consisting of the amino acid sequence each of which is encoded by the above described genes 1 to 7 obtained from the human pancreatic adenocarcinoma cell line Panc-1 or gene KM-PA-2 or KM-PA-4 obtained from the human pancreatic adenocarcinoma cell line CFPAC-1, and preferably, a polypeptide consisting of the amino acid sequence described in any one of those from SEQ ID NO:45 to SEQ ID NO:53. These polypeptides can be used for inducing and/or activating CTL as a tumor antigen. Moreover, these polypeptides can be used as a material for specifying a tumor antigen epitope to obtain a tumor antigen peptide.

A peptide according to the present invention can be obtained by designing peptides, for example, which are suited for the HLA-A2-restricted motif, based on the amino acid sequence of the above-described polypeptide, to select ones recognized by CTL, for example, which activate and/or induce CTL, from the designed peptides. A peptide according to the present invention may be the peptide having a property of a tumor antigen epitope presented on the surface of an antigen-presenting cell through binding to HLA-A2 and recognized by CTL. The peptide consists of amino acid residues of at least about 5 or more, preferably about 7 or more, and more preferably 9 to 10. Particularly preferably, the peptide is one consisting of an amino acid sequence described in any one of those from SEQ ID NO:1 to SEQ ID NO:44. These peptides can be used as a tumor antigen peptide for activating and/or inducing the HLA-A2-restricted tumor-specific cytotoxic T lymphocytes.

For activating and/or inducing CTL, one of the above-described polypeptide or peptide may be used or they may be used in combination of two or more. As described above, CTL is a population consisting of plural cells that recognize various antigens, so that it is recommended to use these peptides preferably in combination of two or more.

A polypeptide or peptide, which has one or several amino acid(s) with a mutation such as deletion, substitution, addition, or insertion introduced into the polypeptide or peptide specified as above and is recognized by at least the HLA-A2-restricted CTL, is also included within the scope of the present invention. A means for introducing mutations such as a deletion, substitution, addition, or insertion is well known and, for example, Ulmer's technique (Science, 219:666, 1983) can be employed. When introducing such mutation, in view of preventing a change of the fundamental properties (such as the physical properties, activity, or immunological activity) of the peptide, mutual substitution among, for example, amino acids having similar properties (polar amino acids, non-polar amino acids, hydrophobic amino acids, hydrophilic amino acids, positively charged amino acids, negatively charged amino acids, aromatic amino acids, and so on) can be carried out. In addition, some modification can be made on these peptides to such an extent that there is no notable change of their function, such as modification of the constitutive amino group or carboxyl group.

(Polynucleotide)

A polynucleotide according to the present invention is a polynucleotide consisting of the nucleotide base sequence described in any one of those from SEQ ID NO:54 to SEQ ID NO:62, which are the nucleotide base sequences of genes 1 to 7 or gene KM-PA-2 or KM-PA-4 obtained from the human pancreatic adenocarcinoma cell line Panc-1 or the human pancreatic adenocarcinoma cell line CFPAC-1 as described above, or the complementary strand thereof. The polynucleotide may also be a polynucleotide encoding each of the peptides consisting of the amino acid sequences described in any one of those from SEQ ID NO:1 to SEQ ID NO:44 or a polypeptide consisting of the amino acid sequence described in any one of SEQ ID NO:45 to SEQ ID NO:53, or the complementary strand thereof. Moreover, the above-described polynucleotide may consist of a nucleotide base sequence of at least about 15 or more, preferably about 21 to 30 or more nucleotides, wherein the nucleotide base sequence corresponds to a region encoding a tumor antigen epitope in the amino acid sequence of the polypeptides according to the present invention, or the complementary strand thereof. Selection of a useful polynucleotide and determination of its nucleotide base sequence are possible, for example, by employing well-known protein expression systems to confirm the ability of the expressed protein to induce and/or activate CTL.

Moreover, a polynucleotide that hybridizes to the above-described polynucleotide under stringent conditions is included in the scope of the present invention. In the case where the polynucleotide molecule is a DNA molecule, “a DNA molecule that hybridizes to a DNA molecule under stringent conditions” can be obtained, for example, by the method described in “Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Laboratory, 1989.)” “To hybridize under stringent conditions” herein means that a positive hybridizing signal is still observed even under the condition in which, for example, hybridization is carried out in a solution containing 6×SSC, 0.5% SDS, and 50% formamide at 42° C. and then, washing is carried out in a solution containing 0.1×SSC and 0.5% SDS at 68° C.

The above-described polynucleotide can induce and/or activate the HLA-A2-restricted CTL, when it is expressed in cells having HLA-A2. In this case, the above-described polynucleotide has a poly(A) structure in its 3′-terminal. The number of poly(A) does not have an influence on the site encoding the amino acid acting as a tumor antigen, so that the number of poly(A,) of the polynucleotide is not limited.

All of the above-described polynucleotides provide genetic information useful for producing a polypeptide or a peptide according to the present invention or can be also utilized as a reagent and a standard of a nucleic acid.

(Recombinant Vector)

A recombinant vector can be obtained by inserting the above-described polynucleotide into an adequate DNA vector. The DNA vector used is properly selected in accordance with the kind of host and the purpose of use. The DNA vector may be a naturally existing one and also may be one that lacks a part of its DNA other than that necessary for replication. For example, vectors can be exemplified as those derived from a chromosome, an episome, and a virus, for example, vectors derived from a bacterial plasmid, derived from a bacteriophage, derived from a transposon, derived from an enzyme episome, derived from an inserting element, and derived from an enzyme chromosome element, for example, vectors derived from a virus such as baculovirus, papovavirus, SV40, vacciniavirus, adenovirus, fowl pox virus, pseudo rabies virus, and retrovirus, and vectors prepared by combination of them, for example, vectors derived from the genetic element of the plasmid and the bacteriophage, for example, a cosmid and a phagemid. Further, an expression vector and a cloning vector etc. can be used in accordance with the desired purpose.

The recombinant vector, which comprises the constitutional elements of the desired DNA sequence and a DNA sequence possessing information relating to replication and regulation, such as a promoter, a ribosome-binding site, a terminator, a signal sequence, an enhancer, and so on, can be prepared by combining them using well-known methods. As a method for inserting the polynucleotide according to the present invention into the above-described DNA vector, the well-known methods can be employed. For example, a method can be used, wherein an appropriate restriction enzyme is chosen for treating a DNA to cleave it at a specific site, and then, the DNA is mixed with the DNA used as a vector treated in the same way, followed by ligating with a ligase. A desired recombinant vector can also be obtained by ligating an adequate linker to the desired polynucleotide followed by inserting the resultant molecule into a multi-cloning site of a vector suitable for a purpose.

(Transformant)

The DNA vector in which the above-described polynucleotide has been inserted can be used to obtain a transformant by transforming a well-known host such as Escherichia coli, yeast, Bacillus subtillis, an insect cell, or a mammalian cell therewith by well-known methods. In the case of carrying out the transformation, a more preferable system is exemplified by the method for integrating the gene in the chromosome, in view of achieving stability of the gene. However, an autonomous replication system using a plasmid can be conveniently used. Introduction of the DNA vector into the host cell can be carried out by standard methods such that described in “Molecular Cloning: A Laboratory Manual” (ed. by Sambrook et al., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, 1989.) Concretely, calcium phosphate transfection, DEAE-dextran-mediated transfection, microinjection, cation lipid-mediated transfection, electroporation, transduction, scrape loading, ballistic introduction and infection can be employed.

(Producing Polypeptide or Peptide)

Using an expression vector as a DNA vector for transduction of the above-described transformant, a polypeptide or a peptide according to the present invention can be provided. A transformant, transformed with a DNA expression vector comprising the above-described polynucleotide, is cultured under well-known culture conditions suitable for each host. Culturing may be conducted by using indicators, such as a function of the polypeptide or a peptide according to the present invention that is expressed by the transformant, particularly at least the activity to induce and/or activate CTL, or the peptide or the amount of the peptide produced in the host or outside of the host. Subculturing or batch culturing may be also carried out using an amount of the transformant in the culture as an indicator.

A peptide according to the present invention can be produced by a general method known in peptide chemistry. For example, “Peptide Synthesis (Maruzen) 1975” and “Peptide Synthesis, Interscience, New York, 1996” are exemplified. However, any widely known method can be used.

A polypeptide or peptide according to the present invention can be purified and collected by a method, such as a gel filtration chromatography, an ion column chromatography, an affinity chromatography, and the like, in combination, or by fractionation means on the basis of a difference in solubility using ammonium sulfate, alcohol, and the like, using a CTL-activating ability of the polypeptide or the peptide as an indicator. More preferably used is a method, wherein the polypeptide or the peptides are specifically adsorbed and collected by using polyclonal antibodies or monoclonal antibodies, which are prepared against the polypeptide or the peptides based on the information of their amino acid sequences.

(Antibody)

An antibody according to the present invention is prepared by using the above-described polypeptide or peptide as an antigen. An antigen may be the above-described polypeptide or peptide itself, or its fragment that is composed of at least 5, more preferably at least 8 to 10 amino acids. In order to prepare the antibody specific to the above-described polypeptide or peptide, a region consisting of the amino acid sequence intrinsic to the above-described polypeptide or peptide is desirably used. The amino acid sequence is not necessarily homologous to the amino acid sequence of the polypeptide or the peptide, but is preferably a site exposed to outside of a stereo-structure of the polypeptide or the peptide. In such a case, it is sufficient that the amino acid sequence of the exposed site is consecutive in the exposed site, even if it may be discrete in its primary structure. The antibody is not limited as long as it binds or recognizes the polypeptide or the peptide immunologically. The presence or absence of the binding or the recognition can be determined by a well-known antigen-antibody binding reaction.

In order to produce an antibody, a well-known method for antibody production can be employed. For example, the antibody is obtained by administration of the polypeptide or peptide according to the present invention to an animal in the presence or absence of an adjuvant with or without linking such to a carrier so as to induce humoral immunity and/or cell-mediated immunity. Any carrier can be used as long as it is not harmful to the host. For example, cellulose, a polymerized amino acid, albumin, and the like are exemplified, but not limited thereto. As an animal used for immunization, a mouse, rat, rabbit, goat, horse, and so on, is preferably used.

A polyclonal antibody can be obtained from serum of an animal subjected to the above-described immunological means by a well-known method for collecting antibodies. A preferable means is exemplified by immunoaffinity chromatography.

A monoclonal antibody can be produced by collecting antibody-producing cells (for example, a lymphocyte derived from a spleen or a lymph node) from the animal subjected to the above-described immunological means, followed by introducing a well-known transformation means with a permanently proliferating cell (for example, myeloma strain such as P3/X63-Ag8 cells.) For example, the antibody-producing cells are fused with the permanent proliferating cells by a well-known method to prepare hybridomas. Then, the hybridomas are subjected to cloning, followed by selecting ones producing the antibody that recognizes specifically the above-described polypeptide or peptide to collect the antibody from a culture solution of the hybridoma.

The polyclonal antibody or the monoclonal antibody thus obtained, which recognizes and binds to the above-described polypeptide or peptide, can be utilized as an antibody for purification, a reagent, a labeling marker and so on.

(Screening and Compound Obtained by Screening)

The above-described polypeptide or peptide, the polynucleotide encoding the same and the complementary strand thereof, the cell transformed based on the information concerning the amino acid sequence and nucleotide base sequence, or the antibody immunologically recognizing the same provide an effective means for screening a substance capable of inducing and/or activating CTL, when using them solely or in combination with each other. The screening method can be constructed utilizing a well-known screening system. For example, as shown in Examples herein, using a system in which the activation of CTL by the antigen-presenting cells that are pulsed with the tumor antigen peptide, is measured on the basis of the amount of IFN-γ production from CTL. Addition of a test substance to the system allows one to select the substance inducing and/or activating CTL and the substance enhancing the induction and/or the activation. This system describes one screening method, but the screening method according to the present invention is not limited thereto.

A compound obtained by the above-described screening method is also part of the present invention. The compound may be a compound enhancing the recognition of the polypeptide or the peptide by CTL through an interaction with the polypeptide or the peptide according to the present invention, and/or HLA-A2. Further, it may be a compound enhancing the expression of the polynucleotide according to the present invention through an interaction with the polynucleotide. The compound thus selected can be used in a pharmaceutical composition by selecting ones having both biological usefulness and low toxicity.

(Pharmaceutical Composition)

The polypeptide or peptide according to the present invention can be used for activating and/or inducing the HLA-A2-restricted tumor-specific cytotoxic T lymphocytes, as a tumor antigen or a tumor antigen peptide. In other words, the method for inducing CTL, which is characterized in that the above-described polypeptide or peptide is used, and a inducer of CTL comprising the above-described polypeptide or peptide are included in the scope of the present invention.

The polypeptide or the peptide according to the present invention, the polynucleotide encoding the polypeptide and the complementary strand thereof, the recombinant vector prepared based on the information of their amino acid sequences and nucleotide base sequences, the cell transformed with the recombinant vector, or the antibody immunologically recognizing the polypeptide or the peptide, the compound enhancing the recognition of the polypeptide or the peptide by CTL through interaction with the polypeptide or the peptide, and/or HLA-A2, or the compound enhancing expression of the polynucleotide through interaction therewith can used a pharmaceutical composition comprising at least one species thereof, when using them solely or in combination with each other.

Concretely, for example, composition consisting of the polypeptide or the peptide according to the present invention, and the pharmaceutical composition comprising the polypeptide or the peptide according to the present invention can be used as a so-called anti-cancer vaccine. In such a case, in order to activate the cell-mediated immunity, the polypeptide or the peptide according to the present invention can be used in the presence or absence of an adjuvant with or without linking such to a carrier. Any carrier can be used as long as it is not harmful to the human body. For example, cellulose, a polymerized amino acid, or albumin is exemplified, but the carrier is not limited thereto. A dosage form is properly chosen from those to which the well-known means for preparing a polypeptide or a peptide are applied. The amount thereof to be administered depends on a degree of recognition of the peptide by CTL, and is generally 0.01 mg to 100 mg/day/adult human body, preferably 0.1 mg to 10 mg/day/adult human body as an amount of active substance. Such an amount is administered once every several days or every several months.

Alternately, an effective action of an anti-cancer vaccine can also be obtained by collecting a mononuclear cell fraction from the peripheral blood of a patient, and culturing the fraction with a peptide according to the present invention, followed by returning the mononuclear cell fraction, in which CTL are induced and/or activated, back into the blood of the patient. Culture conditions, such as the concentration of mononuclear cells and the concentration of the polypeptide or the peptide according to the present invention when they are cultured, can be readily determined. Further, a substance, such as interleukin 2 (IL-2) having an ability to induce the growth of lymphocytes may be added to the culture.

In the case of using the polypeptide or the peptide according to the present invention as an anti-cancer vaccine, using even only one polypeptide or one peptide is effective as an anti-cancer vaccine. However, plural kinds of the above-described polypeptide or peptide can be used in combination. CTL of the cancer patient is the population of cells recognizing various tumor antigens, so that using plural kinds of polypeptides or peptides as an anti-cancer vaccine may give a higher effect than using only one kind.

The above-described composition, inducer of the cytotoxic T lymphocytes, anti-cancer vaccine and pharmaceutical composition are useful for treatment of a cancer disease such as pancreatic cancer, colon cancer, or stomach cancer.

In addition, the polynucleotide encoding the polypeptide according to the present invention and the complementary strand thereof are also useful for gene therapy of a cancer disease such as pancreatic cancer, colon cancer, or stomach cancer.

A method in which these polynucleotides are present in a vector and directly introduced in vivo, and a method in which cells are collected from a donor followed by introducing polynucleotides present in a vector in vitro, can be both utilized. Retrovirus, adenovirus, and vaccinia virus exemplify the vectors, and retrovirus-related ones are preferred. Needless to say, these viruses show deficiency for replication. The amount of administration thereof can depend on the degree of recognition by CTL of the polypeptide encoded by the polynucleotide. Generally, as a DNA content encoding the tumor antigen peptide according to the present invention, the amount ranges from 0.1 μg to 100 mg/day/adult human body, preferably 1 μg to 50 mg/day/adult human body. This amount is administered once every several days or every several months.

(Measuring Method for Diagnosis and Reagent)

The polypeptide or the peptide according to the present invention, the polynucleotide encoding the polypeptide and the complementary strand thereof, and the antibody immunologically recognizing the polypeptide or the peptide can be used independently for a diagnostic marker and a reagent etc. The present invention also provides a reagent kit comprising one or more containers in which one or more species thereof are present. For the preparation thereof, it is sufficient to use a well-known means for their preparation according to each of polypeptide or peptide, polynucleotide, or antibody.

Diagnostic means for a disease related to expression or activity of the polypeptide or the peptide according to the present invention can be carried out, for example, utilizing the interaction or reactivity with the polynucleotide encoding the polypeptide, by determining the existing amount of the corresponding nucleic acid molecule, and/or determining a distribution of the polypeptide or the peptide in an individual living body, and/or determining a presence of the polypeptide or the peptide, and the existing amount in a sample derived from the individual body. In other words, measurement is carried out quantitatively or qualitatively for the polypeptide or the peptide according to the present invention or the polynucleotide encoding the same as the diagnostic marker. As a method for quantitative or qualitative measurement of the polypeptide or the peptide or the nucleic acid encoding the same, which are present in the sample, a well-known method can be utilized. Radio immunoassay, competitive binding assay, Western blotting analysis, ELISA, and the like exemplify such a method. In addition, the nucleic acid molecule can be detected and quantified at an RNA level by using, for example, amplification, polymerase chain reaction (PCR,) RT-PCR, RNase protection, Northern blotting method, and other hybridization methods.

The sample subjected to measurement is exemplified by the cells derived from an individual human body present in for example, blood, urine, saliva, spinal fluid, tissue biopsy, or autopsy material, and the like. The nucleic acid molecule subjected to measurement is obtained from the each sample described above by a well-known method for nucleic acid preparation. For the nucleic acid molecule, genomic DNA can be directly used for detection, or it may be enzymatically amplified by using PCR or any other amplification method before the analysis. RNA or cDNA may be similarly used. In comparing with a normal genotype, a deletion or insertion can be detected in accordance with a size change of an amplification product. Hybridizing the amplified DNA with the labeled DNA encoding the above-described polypeptide can identify point mutations.

Detecting mutation of, reduction of, and increase in the polypeptide according to the present invention and the DNA encoding the polypeptide by the above-described measuring method, makes it possible to diagnose diseases, to which the polypeptide is associated, such as pancreatic cancer, colon cancer, or stomach cancer.

EXAMPLES

The present invention will be illustrated more concretely with the following examples, but is not limited thereto.

Example 1 Establishment of HLA-A2-Restricted CTL

The HLA-A2-restricted tumor-specific cytotoxic T lymphocyte line was established from tumor infiltrating lymphocytes (TIL) of a colon tumor patient (HLA-A0207/3101, HLA-B46/51, HLA-Cw1) (Int. J. CANCER, 81:459-466, 1999; J. Immunol., 163:4994-5004, 1999.) Specifically, TIL obtained from the colon tumor patient was cultured for a long period up to 50 days or longer by adding 100 U/ml of recombinant human interleukin 2 (IL-2.) Every 7 days, a portion of TIL activated by IL-2 was collected and cultured together with various kinds of tumor cells or normal cells to assay its CTL activity by measuring the produced IFN-γ and by measuring ⁵¹Cr released from the cancer cells (J. Immunol., 163:4994-5004, 1999.) IFN-γ was measured by an enzyme-linked immunosorbent assay (ELISA). At day 58 after the start of the culture, OK-CTLp, which is one of sublines showing HLA-A2-restricted tumor-specific CTL activity, was obtained. OK-CTLp obtained is a cell population in which 80% of the cells have a phenotype of CD3⁺CD4⁻CD8⁺ and 20% of the cells have a phenotype of CD3⁺CD4⁺CD8⁻. Using OK-CTLp as an effector cell and culturing it together with various kinds of cells that are used as a target cell, such as a tumor cell, the cytotoxicity to the target cell and activation of OK-CTLp were measured using the ⁵¹Cr-release test and by using IFN-γ production as an indicator, respectively. The results are each presented in FIG. 1 and FIG. 2.

OK-CTLp obtained, as shown in FIGS. 1 and 2, recognized HLA-A0201⁺Panc-1 pancreatic adenocarcinoma cell, SW620 colon adenocarcinoma cell, HLA-A0206⁺KE3 esophageal squamous-cell carcinoma (SCC) cell and HLA-A0207⁺CA9-22 oral SCC cell to produce IFN-γ and represent sufficient cytotoxicity. However, no cytotoxicity was shown against HLA-A2⁻ tumor cells, such as QG56 lung adenocarcinoma cell, RERF-LC-MC lung adenocarcinoma cell, and COLO320 colon adenocarcinoma cell, and autologous Epstein-Barr virus transformed B cell (EBV-B) and autologous phytohemagglutinin (PHA)-blastoid T cells both derived from the normal cells. Further, OK-CTLp lysed all of the HLA-A2⁺ tumor cells tested (R27 breast cancer cell, HAK-2 primary hepatocellular carcinoma cell, SK-MEL-5 melanoma cell, and SF126 astrocytoma cell, which are HLA-A0201⁺, and HLA-A0206⁺ PC9 lung adenocarcinoma cell, and 1-87 lung adenocarcinoma cell and OMC-4 cervical SCC cell, which are HLA-A0207⁺.) The CTL activity was inhibited by an anti-HLA class I monoclonal antibody (mAb), an anti-CD8 mAb or an anti-HLA-A2 mAb, but not inhibited by other mAbs (FIG. 2.) This result revealed that OK-CTLp recognizes the above-described tumor cells in a HLA-A2-restricted manner and shows cytotoxicity.

Meanwhile, the genotype of the HLA class I alleles of the above-described tumor cells has been disclosed (J. Immunol., 163:4994-5004, 1999.) The serotype of the HLA class I of the above-described patients was determined by applying a conventional method using the peripheral blood mononuclear cells (PBMC). In addition, the HLA-A2 subtype was determined by a sequence-specific oligonucleotide probe method and direct DNA sequencing. The phenotype of OK-CTLp was analyzed by direct immunofluorescence analysis using anti-CD3 mAb, anti-CD4 mAb, or anti-CD8 mAb (made by Nichirei) or anti-TCRαβ mAb (WT31, Becton Dickinson), which were labeled with fluorescein isothiocyanate (FITC). In addition, the antibodies used to analyze for HLA-A2 restriction and specificity of OK-CTLp were anti-HLA class I mAb (W6/32, IgG2a,) anti-HLA-A2 mAb (BB7.2, IgG 2b,) anti-CD8 mAb (Nu-Ts/c, IgG2a,) anti-HLA class IImAb (H-DR-1, IgG2A,) and anti-CD4mAb (Nu-Th/i, IgG1.) Anti-CD13 mAb (MCS-2, IgG2a) and Anti-CD14 mAb (JML-H14, IgG1) were used as an isotype-matching control mAb.

Example 2 Isolation and Identification of cDNA Clone Encoding Tumor Antigen

A gene encoding the tumor antigen of the Panc-1 tumor cell recognized by OK-CTLp was isolated and identified according to the well-known gene expression cloning method (J. Immunol., 163:4994-5004, 1999.) Specifically, poly(A)⁺RNA of the Panc-1 tumor cells was converted to cDNA, and ligated with a SalI adapter so as to insert into the expression vector pCMV-SPORT-2 (Invitrogen Corp.)

cDNAs of HLA-A0207, HLA-A2402, or HLA-A2601 were obtained by reverse transcriptase polymerase chain reaction (RT-PCR) and cloned into the eukaryote expression vector pCR3 (Invitrogen Corp.)

200 ng of the above-described plasmid DNA pool or clones of Panc-1 cell cDNA library was mixed with 200 ng of the cDNA of HLA-A0207 in 100 μl of Opti-MEM (Invitrogen Corp.) for 30 min. 50 μl of this mixture was added to COS-7 cells (5×10³) and incubated for 6 h in a 96-well U-bottom type microculture plate (Nunc Corp.) for co-tranduction. Then, RPMI-1640 culture medium containing 10% FCS was added to and culturing was carried out for 2 days, followed by the addition of OK-CTLp (5×10⁴) to each well. After a further 18 h incubation, 100 μl of the supernatant was collected and IFN-γ production was measured thereon by ELISA. In this case, using COS-7 cells to which the gene had not been transfected as a target, IFN-γ production by OK-CTLp was examined and the value of IFN-γ produced was subtracted as a background from that of each measurement. As a result, seven cDNA clones were obtained, which enhanced IFN-γ production by OK-CTLp through recognition by OK-CTLp.

The nucleotide sequence of the seven cDNA clones obtained was determined by dideoxynucleotide sequencing method using a DNA sequencing kit (Perkin Elmer Corp.) and using an ABI PRISM™ 377DNA sequencer (Perkin Elmer Corp.) In addition, the amino acid sequence encoded by each clone was deduced from the nucleotide base sequence. Also, a homology search of the nucleotide base sequence of these clones was conducted through accessing GenBank. The results are presented in the above-described Table 1. With regard to clone 3 among the seven cDNA clones (clones 1 to 7) obtained, the sequence of an initial clone, which was obtained by the gene expression cloning method described above, was 25 bp shorter at the 5′-terminal region than that of WHSC2 showing high homology, so that full-length cDNA was obtained from the cDNA library of the Panc-1 cell by a standard colony hybridization method using the clone labeled with ³²P as a probe.

As shown in FIGS. 3A and 3B, clones 1 to 7 were each recognized by OK-CTLp to enhance IFN-γ production of OK-CTLp. However, OK-CTLp did not recognize COS-7 cells to which HLA-A0207 cDNA and the cDNA clone used as a negative control were cotransfected, or COS-7 cells to which any one of cDNA clones 1 to 7 and the cDNA of HLA-A2402 or HLA-A2601 were cotransfected, and did not show the IFN-γ production. When various concentrations of cDNA clones 1 to 6 were cotransfected into COS-7 cells together with 100 ng of HLA-A0207 cDNA or HLA-A2402 cDNA, IFN-γ production by OK-CTL was observed in a dose-dependent manner (FIGS. 4A to 4F.)

Expression of the mRNA of these genes was examined by Northern blotting analysis. The same expression pattern was observed except for gene 5. These genes are expressed commonly in the tumor cells and normal cells. However, expression levels in tumor cells such as Panc-1 cell, SW620 cell, and CA9-22 cell were significantly higher than that in normal cells, such as the T cell stimulated by PHA and a B cell transformed by Epstein-Barr virus (EBV-B). Expression of mRNA of gene 5 was barely detected under these experimental conditions. The reason may be that expression of gene 5 is rare as proven by the fact that colony hybridization using clone 5 labeled with ³²P gives only 3 clones from an about 1×10⁶ library.

Example 3 Establishing OK-CTL Clone

Since CTL activated by recognizing the tumor antigen is a population of cells recognizing plural kinds of tumor antigens, the above-described OK-CTLp was subjected to cloning by limiting dilution culture (0.3, 0.5, 1, 2, and 4 cells/well) to obtain an OK-CTL clone (J. Immunol., 163:4994-5004, 1999.) These clones are those having CTL activity selected by culturing them together with COS-7 cells into which 100 ng/well of any one of the above-described seven cDNA clones and 100 ng/well of HLA-A0207 cDNA were cotransfected, or with the tumor cells, in a cell ratio of 1:1, and measuring IFN-γ production. Specifically, three hundred CTL clones were obtained from the parent line OK-CTLp by a limiting dilution culture. Eighty CTL clones among them had HLA-A2-restricted tumor-specific CTL activity and expressed the phenotype of CD3⁺CD4⁻CD8⁺ and TCR αβ⁺. Among them, 2, 3, 1, 3, 2, and 4 CTL clones showed reactivity to the COS-7 cells expressing clone 1, clone2, clone 3, clone 4, clone 5, and clone6, respectively. In other words, it was revealed that the tumor antigen recognized by CTL differs in accordance with the CTL clones. Table 4 shows data of fifteen typical CTL clones. This suggested that OK-CTLp, i.e., CTL derived from the cancer patient, is a population of cells recognizing plural kinds of tumor antigens.

TABLE 4 cDNA expressed in COS-7 cell together with HLA-A0207 cDNA clone 6 clone 1 clone 2 clone 3 clone 4 Clone 5 (2-5 no CTL clone (UBE2V) (HNRPL) (WHSC2) (EIF4EBP1) (ppMAPkkk) OAS3) cDNA Panc-1 2-2-H3 110 0 0 0 0 0 0 340 2-1-H12 134 0 0 0 0 0 0 264 1-2-D7 0 200 0 0 0 0 0 235 1-2-D12 0 >1000 0 0 0 0 0 >1000 4-1-H8 0 133 0 0 0 0 0 84 4-2-A11 0 0 100 0 0 0 0 725 0.5-1-H12 0 0 0 >1000 0 0 0 >1000 0.5-1-D6 19 0 0 118 0 13 0 448 4-2-B3 0 0 0 95 0 0 0 100 2-1-F4 0 0 0 0 >1000 0 0 >1000 0.5-1-H2 0 0 0 0 81 0 0 122 0.5-1-D7 27 34 0 0 0 110 0 304 0.5-2-A4 0 0 0 0 0 113 0 >1000 1-2-D1 21 0 22 44 0 61 0 78 2-2-B4 0 0 0 0 0 >1000 0 >1000

Example 4 Preparation of Tumor Antigen Peptide and Its CTL-Inducing Activity

In order to obtain the tumor antigen peptide derived from the seven tumor antigen genes, which were obtained in Example 2 and can induce CTL in a HLA-A2-restricted manner, a peptide having an HLA-A2 binding motif (a specific sequence) was searched for in the literature (J. Immunol., 152:163, 1994; Immunogenetics, 41:178, 1994,) and peptides of 9-mer to 11-mer, which were different from each other and suited to the motif obtained, was designed and synthesized based on the amino acid sequence encoded by the above-described genes 1 to 7 and the amino acid sequence of UBE2V, HNRPL, WHSC2, EIF4EBP1, ppMAPkkk, 2-5 OAS3, and CPSF having high homology with these genes. The purity of the peptides obtained was each 70% or higher.

Binding activity of the peptide to the HLA-A0201 molecule was tested using a T2 cell mutant strain (Cancer Res., 54:1071-1076, 1994.) The T2 cell expresses the HLA-A2 molecule on a cell surface without binding to a peptide, because of deficiency of TAP. Specifically, the synthesized peptide (10 μM) and the T2 cells were incubated at 26° C. for 3 h and, subsequently, incubated in 5% CO₂and 95% air at 37° C. for 3 h. Thus, T2 cells, on whose surface the peptide was presented by HLA-A2, were obtained. The cells were incubated together with anti-HLA-A2 mAb (BB7.2) followed by staining with R-phycoerythrin linked F (ab′)₂ rabbit anti-mouse immunoglobulin (Ig) (DAKO Corp.) Then, the expression pattern was analyzed by employing FACScan (Beckman Dickinson Corp.), which resulted in confirmation that HLA-A0201 molecules with the peptide were expressed on the cell surface.

In order to test for recognition of a peptide by CTL, the T2 cells previously pulsed with each peptide (10 μM) was used as a target cell (T), and OK-CTLp or OK-CTL clone was used as an effector cell (E). The target cell and the effector cell were incubated for 18 h, the supernatant collected, followed by measuring IFN-γ contained in the supernatant by an ELISA. In the case where OK-CTLp was used as the effector, an E/T ratio was set to 10:1. In the case where the OK-CTL clone was used, it was set to 2:1 to conduct the test. On the other hand, in case where the OK-CTL clone was used to test for the CTL activating ability of the peptide, the clone was used which recognized the gene product encoding the peptide being examined. Using IFN-γ production of OK-CTLp or OK-CTL clone against the T2 cells, which had not been pulsed with the peptide, as a background, subtraction was performed from each measurement value. The results were shown in FIGS. 5 to 10. FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, and FIG. 10 each show the result of the peptide derived from gene 1 and UBE2V, gene 2 and HNRPL, gene 3 and WHSC2, gene 4 and EIF4EBP1, and gene 5 and ppMAPkkk, and gene 6 and 2-5 OAS3.

Moreover, the various concentrations of each peptide were used for incubation together with the T2 cells to examine the CTL clone-activating ability, resulting in finding that the CTL clone can be activated by each peptide in a dose-dependent manner. Representative examples of peptides derived from gene 1 and UBE2V, gene 2 and HNRPL, gene 3 and WHSC2, gene 4 and EIF4EBP1, gene 5 and ppMAPkkk, and gene 6 and 2-5 OAS3 were presented in FIGS. 11A-11F, respectively. On the other hand, Table 5 shows peptides derived from gene 7 and CPSF. In Table 5, the peptide derived from EBV and the peptide derived from influenza virus are positive controls, which can activate CTL.

As the result of these experiments, it was revealed that the peptides shown in Table 2 described-above can activate OK-CTLp and/or OK-CTL clone to produce IFN-γ.

TABLE 5 IFN-γ production (pg/ml) Concentration of peptide Peptide 0.1 μM 1 μM 10 μM 50 μM Derived 0 93 693 35 from influenza virus Derived 119 390 371 117 from EBV P20 344 643 0 34 P21 428 501 81 195 P22 254 1027 431 407 P23 6360 0 345 160 P24 728 Detection 103 2 limit or higher P25 69 1569 25 122 P26 141 418 1239 0 P27 352 889 250 0 P28 898 Detection 0 144 limit or higher P29 0 Detection 86 362 limit or higher P30 88 7001 Detection Detection limit or higher limit or higher P31 443 Detection Detection 314 limit or higher limit or higher

Example 5 CTL Induction from Peripheral Blood Mononuclear Cells Derived from Cancer Patient by a Peptide

Among the peptides that were able to enhance IFN-γ production from the OK-CTLp or OK-CTL clone in Example 4, those from P1 to P19 were examined for their ability to induce CTL from peripheral blood mononuclear cells derived from a cancer patient. The method for inducing CTL by a peptide was according to the well-known method (J. Exp. Med., 187:277-288, 1998; Cancer Res., 59:4056-4063, 1999.) Specifically, autologous peripheral blood mononuclear cells (PBMC) derived from a cancer patient, from whom OK-CTLp was obtained, were incubated together with the peptide (10 μM.) The cells were re-stimulated at day 10 and 14 after the start of culturing, using autologous PBMCs as an antigen presenting cell (APC) which were pulsed with 10 μM of the same peptide for 2 h and exposed to irradiation (30 gray.) At day 21 after the start of culturing, the cells were collected to test for surface phenotype. In addition, the cells were examined for the recognition of various target cells, using IFN-γ production measured by ELISA when they were cultured together with the target cells as an indicator. As a target cells, SW620 cell, CA9-22 cell, and Panc-1 cell, which are the HLA-A2⁺ tumor cells, were used. The result was shown in Table 6.

TABLE 6 IFN-γ production (pg/ml) from peripheral blood mononuclear cells in recognition of various target cells QG56 RERF-LC-MS COLO320 SW620 CA9-22 Panc-1 (HLA-A26/ (HLA-A11/ (HLA-A24/ (HLA-A0201/ (HLA-A0207/ (HLA-A0201/ Peptide MFI 26) 11) 24) 24) 24) 11) P1 571 0 26 50 235 81 492 P2 607 0 0 5 53 0 0 P3 910 0 0 44 188 58 289 P4 1008 0 0 0 60 0 0 P5 637 0 0 38 500 96 638 P6 819 0 8 40 344 863 527 P7 783 0 0 0 344 0 54 P8 499 0 26 0 142 165 186 P9 832 0 27 0 194 98 339 P10 504 0 0 0 108 130 163 P11 1089 0 0 0 893 62 >1000 P12 780 0 0 40 46 0 197 P13 656 0 15 0 151 95 115 P14 591 0 0 0 112 184 265 P15 789 0 32 0 199 219 502 P16 887 0 0 0 0 147 113 P17 660 0 0 0 >1000 >1000 691 P18 657 29 0 0 >1000 70 >1000 P19 775 0 30 66 55 48 105 no 491 0 0 36 0 0 17 Peptide

PBMC stimulated in vitro using P1, P3, P5, P6, P8, P9, P10, P11, P13, P14, P15, P17, or P18 among the 19 peptides recognized SW620 cells, CA9-22 cells and Panc-1 cells, which are the HLA-A2⁺ tumor cells, produced IFN-γ in a significant amount. However, the PBMC barely recognized the HLA-A2⁻ tumor cell. On the other hand, P2, P4, P7, P12, and P16 also induced CTL recognizing any one of the HLA-A2⁺ tumor cells. PBMC stimulated by P19 recognized not only the tumor cells expressing HLA-A2, but also the tumor cells expressing other types of HLA. IFN-γ production from these CTL was inhibited by anti-HLA class I mAb, anti-CD8 mAb, or anti-HLA-A2 mAb, and not inhibited by other mAbs. In addition, when peripheral blood mononuclear cells (PBMC) were prepared from blood of two HLA-A0201₊ patients (a colon cancer patient and a pancreatic cancer patient) to examine CTL induction by the peptides, the same result as above was obtained. In other words, it was found that the above-described peptides can induce HLA-A2-restricted CTL from the peripheral blood mononuclear cells of the patient.

Binding affinity of the peptides to HLA-A0201 molecule was expressed as a relative mean fluorescence intensity (MFI) of the HLA-A2 molecule. The MFI of positive and negative controls were 898 and 490, respectively. It can be supposed that binding affinity of a peptide to the HLA-A0201 molecule has no correlation with induction of CTL by the peptide.

Moreover, CTL-activating ability of these 19 peptides was directly examined in a ⁵¹Cr-releasing test using toxicity to the target cells as an indicator. Specifically, the above-described PBMC, in which CTL was induced, was further recultured to proliferate in the presence of autologous APC, IL-2, and a corresponding peptide. At about day 21 to 28 after the start of reculturing, PBMC was collected and cytotoxicity thereof was tested again by measuring IFN-γ and by a 6-h ⁵¹Cr-releasing test. The results were shown in FIGS. 12 to 17. PBMC of the cancer patient, which was stimulated by these peptides, lysed the HLA-A2⁺ tumor cells. However, the autologous EBV-B cells and the T cells stimulated by PHA, both of which were derived from normal cells and were expressing HLA-A2, and the HLA-A2⁻ tumor cell RERF-LC-MS, were not lysed. However, PBMC stimulated by peptides P14, P15, and P17 also showed cytotoxicity to the autologous EBV-B cells. Moreover, PBMC stimulated by P19 showed high cytotoxicity to the autologous EBV-B cells. In addition, PBMC stimulated by these peptides showed cytotoxicity to the T2 cells, which was pulsed with the same peptide as that used for stimulation of PBMC, in a dose dependent manner. Typical examples are shown in FIGS. 18A-18E. From these above, it was found that the above-described peptides can induce CTL, which shows HLA-A2-restricted cytotoxicity, from the peripheral blood mononuclear cells of the cancer patient.

Example 6 CTL Induction from Peripheral Blood Mononuclear Cell of Patient by Peptide

For six peptides (P21, P22, P24, P26, P30, and P32) with a purity of 95% or higher among peptides from P20 to P32 derived from gene 7 and CPSF among the tumor antigen peptide obtained in Example 4, the activity to induce CTL in vitro from human peripheral blood mononuclear cells (PBMC) was examined using IFN-γ production as an indicator. PBMC used was prepared from each peripheral blood of sixteen HLA-A2-positive cancer patients (4 patients with pancreatic cancer, seven patients with stomach cancer, and 5 patients with colon cancer) and six healthy individuals. Specifically, 1×10⁵ PBMC was added to each well of 96-well U-bottom type microculture plate (Nunc Corp.) and incubated together with 10 μM of each of the above-described peptides in 200 μl culture medium. The culture medium consisted of 45% RPMI-1640, 45% AIM-V (Invitrogen Corp.,) 10% fetal calf serum (FCS), 100 U/ml of human interleukin-2, and 0.1 μM MEM nonessential amino acid solution (Invitrogen Corp.). At day 4 and day 7 after the start of culturing, half of the culture medium was removed and replaced with the above-described composition containing each corresponding peptide. At-day 10 after the start of culturing, the cells were collected and washed, followed by reacting with T2 cells, which were pulsed with each corresponding peptide, to measure the amount of IFN-γ produced.

Meanwhile, the above-described cells cultured for 10 days after stimulation by the peptide were further cultured for 10 days. The cytotoxicity of the obtained cells against the Panc-1 pancreatic adenocarcinoma cell (HLA-A2) was measured by the standard 6-h ⁵¹Cr-releasing test in an E/T ratio of 10:1. The results obtained are presented as % specific lysis (table 7). Together with this step, cytotoxicity against SSTW-9 tumor cell as the HLA-A2⁻ tumor cell was measured to use as a background that was subtracted from the above-described result.

As a result, induction of HLA-A2-restricted CTL from PBMC by P21, P22, P23, P26, P30, and P32, which was specific to each peptide, was observed in patients of 31% (5/16,) 38% (6/16,) 25% (4/6,) 31% (5/16,) 44% (7/16,) and 7% (1/16) of the above-described sixteen patients, respectively. On the other hand, induction of CTL by P21 and P22 from the PBMC of healthy individuals was found in 50% (3/6) and 33% (2/6,) respectively. However, the other peptides did not induce CTL from the PBMC of healthy individuals (Table 7). The above-described CTL induced from PBMC of the cancer patients by using the peptide showed cytotoxicity against Panc-1 pancreatic adenocarcinoma cell, and also SW620 colon adenocarcinoma cell (HLA-A2/A24) and KWS stomach adenocarcinoma cell (HLA-A2), both of which are the HLA-A2⁺ tumor cells. However, lysis was not observed in SSTW9 stomach adenocarcinoma cell (HLA-A24), which is the HIA-A2⁻ tumor cell, or the PHA-blastoid T cells or the EBV-B transformed B cells, both of which express HLA-A2 and are not the tumor cells. Recognition of the tumor cell by the above-described CTL was inhibited by anti-HLA class I mAb, anti-CD8 mAb, or anti-HLA-A2 mAb, and not inhibited by other mAb.

TABLE 7 INF-γ production (pg/ml)/% specific lysis Origin of PBMC P21 P22 P23 P26 P30 P32 pancreatic 1 0 0 0 0 0 0 cancer 2 7 38/37 41/53 35/36 12 12 patient 3 0 0 0 0 0 0 4 543/12  8 72/10 77/20 73/11 0 stomach 5 0 0 0 53/11 0 0 cancer 6 0 0 0 0 0 0 patient 7 0 0 46/10 0 0 0 8 5 0 0 11 146/18  0 9 1500</27    0 0 8 92 0 10 0 0 0 0 46/26 0 11 136/18  0 0 0 0 0 colon cancer 12 0 92/28 71/18 0 0 57/18 patient 13 0 179 138/10  0 41/12 0 14 66/11 80/19 48 0 33/10 0 15 0 5 14 40/12 0 0 16 140 0 0 45 68 4 healthy HD1 0 0 0 0 0 0 individuals HD2 0 0 13 0 0 0 HD3 58 0 8 0 14 0 HD4 5 0 6 0 0 0 HD5 224 0 83 13 0 0 HD6 97 14 45 0 0 0

Example 7 Isolation and Identification of cDNA Encoding Tumor Antigen

From the genes encoding the tumor antigens (Biochim. Biophys. Res. Commun., 81:936-944, 2001), which were detected by the SEREX (Serological Analysis of Recombinant cDNA Expression Libraries) method (Proc. Natl Acad. Sci. USA, 92:11910-11813, 1995) and already reported, two tumor antigen genes, KM-PA-2 and KM-PA-4, which can activate HLA-A2-restricted CTL, were found by using the same method as that of Example 2. Specifically, cDNA clones each encoding KM-PA-2, KM-PA-4, KM-PA-5, KM-PA-14, KM-PA-15, or KM-PA-18 were packaged in pBluescript vector, and digested by EcoRI and XhoI to insert into pCMV-SPORT2. These cDNAs in various concentrations were each coexpressed in COS-7 cells together with HLA-A0207 or HLA-A2402. Using the COS-7 cells as a target cell, incubation was performed together with OK-CTLp. As a result, COS-7 cells, to which KM-PA-2 or KM-PA-4 was cotransfected with HLA-A0207, induced IFN-γ production from OK-CTLp, in a dose dependent manner of the gene (FIGS. 19A-19B.) The SEREX method is a method for detection of the tumor antigen. However, among 1500 or more kinds of tumor antigens detected by this method, those identified as tumor antigens capable of inducing both cell-mediated immunity and humoral immunity are only MAGE-1, tyrosinase, and NY-ESO-1. Therefore, even a gene identified by the SEREX method as encoding the tumor antigen cannot always activate CTL. It was first found that the above-described tumor antigen genes, KM-PA-2 and KM-PA-4, can activate CTL in an HLA-A2-restricted manner.

Example 8 Preparation of Tumor Antigen and Activity for Inducing CTL from PBMC of Cancer Patient

In order to obtain the tumor antigen peptide derived from the tumor antigen genes, KM-PA-2 and KM-PA-4, obtained from Example 7, different peptides of 9-mer or 10-mer were designed based on the amino acid sequences encoded by KM-PA-2 and KM-PA-4 and synthesized by a well-known method, in the same way as that in Example 4.

The ability of the synthesized peptide to induce CTL from the peripheral blood mononuclear cells of the colon cancer patient, from whom OK-CTLp was obtained, was examined in the same way as that in Example 6. As a result, as shown in FIGS. 20A-20B, PBMC that was stimulated in vitro using any one of peptides P33 to P41 (SEQ ID NO: 33 to SEQ ID NO:41) derived from KM-PA-2 and peptides P42 to P44 (SEQ ID NO:42 to SEQ ID NO:44) derived from KM-PA-4, produced IFN-γ through recognition of the T2 cells (left-hand figure of FIGS. 20A-20B,) which were pulsed with the peptide corresponding to that used for stimulation of the PBMC, and the Panc-1 cell (right-hand of FIGS. 20A-20B,) which is the HLA-A2⁺ tumor cell. However, the PBMC reacted merely to the HLA-A2⁻ tumor cell. As a result, it was revealed that any one of the above-described twelve peptides can induce the antigen specific CTL from PBMC of the cancer patient in an HLA-A2-restricted manner and that the induced CTL can recognize the above-described peptides to produce IFN-γ in an HLA-A2-restricted manner. In addition, cytotoxicity of these CTLs induced by the peptides was directly confirmed by the ⁵¹Cr-releasing test in the same way as that in Example 6. FIGS. 21A-21C show a representative example of the result. As shown in FIGS. 21A-21C, CTLs induced from PBMC of the cancer patient by P35, P39, or P40 lysed Panc-1 cells and YPK-3 cells, both of which are HLA-A2⁺ tumor cells. However, the HLA-A2⁻ tumor cell PaCa-2, the EBV-B cell line OKAB2, and the T cells stimulated by PHA, was not lysed. In other words, it was revealed that the above-described peptides can induce CTL showing cytotoxicity from the peripheral blood mononuclear cells of the cancer patient in an HIA-A2-restricted manner. Further, CTL was also induced by the above-described peptides from PBMC obtained from the cancer patient, such as a pancreatic cancer patient, in addition to the colon cancer patient from whom OK-CTLp was obtained.

Example 9

In order to determine the phenotype of TCR expressed on the cell surface of the CTL clone recognizing the above-described peptide, total RNA of each clone was obtained from each 5×10⁶ CTL clones, which were obtained in Example 3, using RNAzol™ B (TEL-TEST Corp.) cDNA was prepared using the SuperScrip™ Preamplification System (Invitrogen Corp.) for first strand cDNA synthesis. Single stranded cDNA was amplified by polymerase chain reaction (PCR) using one of the 22 different Vβ primers (Vβ1 to 20) and 3′C β primers. PCR was performed for 35 cycles, wherein 1 cycle comprised denaturation at 94° C. for 1 min, annealing at 58° C. for 2 min, and extension at 72° C. for 3 min. The PCR product was inserted into plasmid pCR2 followed by transformation into Escherichia coli using the TA cloning system (Invitrogen Corp.), selection of colonies, and plasmid preparation for determining the cDNA sequence.

As the result, two each of CTL clones reacting with the peptides derived from UBE2V and gene 1, the peptide derived from HNRPL and gene 2, and the peptide derived from 2-5 OAS3 and gene 6, expressed TCR-Vβ 8.1, TCR-Vβ 3.2, and TCR-Vβ 14, respectively. In addition, CTL clones recognizing the peptide derived from WHSC2 and gene 3, the peptide derived from EIF4EBP1 and gene 4, the peptide derived from ppMAPkkk and gene 5, expressed TCR-Vβ 13.1, TCR-Vβ 8.1, and TCR-Vβ 18, respectively (Table 8-1 and Table 8-2).

Two each of CTL clones recognizing the peptide derived from UBE2V and gene 1, the peptide derived from HNRPL and gene 2, and the peptide derived from 2-5 OAS3 and gene 6, expressed TCR possessing different complementarity-determining regions 3 (CDR3) (an element responsible for binding to the antigenic epitopes on the groove of the HLA class I molecules), respectively. CTL clones recognizing the peptide derived from WHSC2 and gene 3, the peptide derived from EIF4EBP1 and gene 4, the peptide derived from ppMAPkkk and gene 5, expressed TCR possessing different CDR3, respectively. The amino acid sequence of each CDR3 is that shown with an underline in Table 8-2.

TABLE 8-1 CTL clone Epitopes Vβ Dβ Jβ Cβ 2-2-H3 UBE2V 43-51 8.1 2.1 2.3 2 2-1-H12 UBE2V 43-51 8.1 2.1 2.3 2 1-2-D7 HNRPL 140-148 3.2 1.1 2.7 2 1-2-D12 HNRPL 140-148 3.2 1.1 2.7 2 4-2-A11 WHSC2 103-111 13.1 2.1 2.7 2 4-2-B3 EIF4EBP1 51-59 8.1 1.1 1.1 1 0.5-1-H2 ppMAPkkk 18 1.1 1.1 1 432-440 1-2-D1 2-5 OAS3 666-674 14 2.1 2.3 2 2-2-B4 2-5 OAS3 666-674 14 2.1 2.3 2

TABLE 8-2 CTL clone Vβ Dβ* Cβ 2-2-H3 IYFNNNVPIDDSGMPE SLGLAGGEQFFGPG EDLKNVFPPE DRFSAKMPNASFSTLK TRLTVL IQPSEPRDSAVYFCAS 2-1-H12 IYFNNNVPIDDSGMPE SLGLAGGEQFFGPG EDLKNVFPPE DRFSAKMPNASFSTLK TRLTVL IQPSEPRDSAVYFCAS 1-2-D7 VSREKKERFSLILESA SLDRSYEQYFGPGT EDLKNVFPPE STNQTSMYLCAS RLTVT 1-2-D12 VSREKKERFSLILESA SLDRSYEQYFGPGT EDLKNVFPPE STNQTSMYLCAS RLTVT 4-2-A11 QGEVPNGYNVSRSTTE SYGGGSSYEQYFGP EDLKNVFPPE DFPLRLLSAAPSQTSV GTRLTVT YFCAS 4-2-B3 IYFNNNVPIDDSGMPE SRVSGEAFFGQGTR EDLKNVFPPE DRFSAKMPNASFSTLK LTVV IQPSEPRDSAVYFCAS 0.5-1-H2 DESGMPKERFSAEFPK SPTELDTEAFFGQG EDLKNVFPPE EGPSILRIQQVVRGDS TRLTVV AAYFCAS 1-2-D1 VSRKEKRNFPLILESP GGSTDTQYFGPGTR EDLKNVFPPE SPNQTSLYFCAS LTVL 2-2-B4 VSRKEKRNFPLILESP GGSTDTQYFGPGTR EDLKNVFPPE SPNQTSLYFCAS LTVL

INDUSTRIAL APPLICABILITY

According to the present invention, HLA-A2-restricted cytotoxic T lymphocytes can be induced, which makes it possible to achieve a specific immunotherapy for pancreatic cancer, colon cancer, and stomach cancer. HLA-A2 alleles are found in 23% of African Blacks, 53% of Chinese, 40% of Japanese, 49% of Northern Caucasians, and 38% of Southern Caucasians. Consequently, the present invention can be expected its great contribution to cancer therapy. Moreover, the present invention greatly contributes to fundamental research on the molecule related to recognition by T cells of a pancreatic cancer cell, a colon cancer cell, stomach cancer, and so on. 

1. An isolated polypeptide consisting of the amino acid sequence of SEQ ID NO:48 or a peptide fragment thereof, wherein said fragment is selected from the group consisting of SEQ ID NO:14 and SEQ ID NO:15.
 2. A composition comprising a polypeptide consisting of the amino acid sequence of SEQ ID NO:48 or a peptide fragment thereof, wherein said fragment is Selected from the group consisting of SEQ ID NO:14 and SEQ ID NO:15, and a pharmaceutically acceptable carrier.
 3. A method for inducing cytotoxic T lymphocytes, comprising contacting, in vitro, “lymphocytes with a composition comprising peripheral blood-mononuclear cells incubated together with a peptide fragment selected from the group consisting of SEQ ID NO:14 and SEQ ID NO:15, wherein the”. lymphocytes contain HLA-A2-restricted cytotoxic T lymphocytes. 